Theory of Beam Scanning for Slot Array Antenna Excited by Slow Wave

The operating principle of a very special type of slot array antennas excited by a slow-wave mode is presented. The arrays exhibit beam-scanning capability with mechanical rotation about the aperture-normal axis. The relation between the rotation angle and the scan angle is deduced. Numerical results for beam scanning are shown, and other performance characteristics including frequency scan, bandwidth, and polarization of the antennas are presented. Important differences of the characteristic features from that of a conventional array are discussed.